May be a problem, but I had that happen to me once about a year ago. Cranked for a long time without starting. Tried again a minute later and it started normally. No problem since. Maybe a one time glitch.

Mine (2011 5.7) started out with a crank-but-no-fire once every few months. When it got to a once-every-few-days thing, I took it to the dealer. It turned out to be a fuel pump relay. Service guy said it was a common issue and he kept a couple of relays in stock. At the time I had mine fixed, the relays were on National back order. Haven't had a problem since.